The overall objective of this project is the development, implementation and evaluation of a computer technology to detect potential therapeutic problems and to provide on-line prospective intervention in the process of health care delivery in the area of drug therapy. The project involves a compilation, maintenance and updating of a rigorously-documented computer-stored knowledge base of information concerning inappropriate or sub-optimal drug use and drug-lab test interaction. Assessment of the magnitude of the problem (i.e. patient exposure) for each category of sub-optimal drug use will be carried out, and the effects of computer intervention on process and outcome will be evaluated.